/*
 * Created on Apr 13, 2004
 * Created by Alon Rohter
 * Copyright (C) Azureus Software, Inc, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 * 
 */

package org.gudy.azureus2.core3.util;

import java.nio.ByteBuffer;

/**
 * SHA-1 hasher utility frontend.
 */
public final class SHA1Hasher {
    private final SHA1 sha1;

    /**
     * Create a new SHA1Hasher instance
     */
    public SHA1Hasher() {
        sha1 = new SHA1();
    }

    /**
     * Calculate the SHA-1 hash for the given bytes.
     * 
     * @param bytes
     *            data to hash
     * @return 20-byte hash
     */
    public byte[] calculateHash(byte[] bytes) {
        ByteBuffer buff = ByteBuffer.wrap(bytes);
        return calculateHash(buff);
    }

    /**
     * Calculate the SHA-1 hash for the given buffer.
     * 
     * @param buffer
     *            data to hash
     * @return 20-byte hash
     */
    public byte[] calculateHash(ByteBuffer buffer) {
        sha1.reset();
        return sha1.digest(buffer);
    }

    /**
     * Start or continue a hash calculation with the given data.
     * 
     * @param data
     *            input
     */
    public void update(byte[] data) {
        update(ByteBuffer.wrap(data));
    }

    /**
     * Start or continue a hash calculation with the given data, starting at the given position, for the given length.
     * 
     * @param data
     *            input
     * @param pos
     *            start position
     * @param len
     *            length
     */
    public void update(byte[] data, int pos, int len) {
        update(ByteBuffer.wrap(data, pos, len));
    }

    /**
     * Start or continue a hash calculation with the given data.
     * 
     * @param buffer
     *            data input
     */
    public void update(ByteBuffer buffer) {
        sha1.update(buffer);
    }

    /**
     * Finish the hash calculation.
     * 
     * @return 20-byte hash
     */
    public byte[] getDigest() {
        return sha1.digest();
    }

    public HashWrapper getHash() {
        return new HashWrapper(sha1.digest());
    }

    /**
     * Resets the hash calculation.
     */
    public void reset() {
        sha1.reset();
    }

    /**
     * Save the current hasher state for later resuming.
     */
    public void saveHashState() {
        sha1.saveState();
    }

    /**
     * Restore the hasher state from previous save.
     */
    public void restoreHashState() {
        sha1.restoreState();
    }

}
